Prior syntheses of the efficacy literature on child and adolescent psychotherapy have shown that, overall, psychotherapy effects are generally positive. However, there currently is debate on the generalizability of these findings to clinical conditions representative of typical mental health services in the community. Thus, child and adolescent psychotherapy appears to be efficacious, but it may not be effective in natural clinic-based settings. The specific aim of this project is to conduct a broad meta-analysis that examines the effectiveness of child and adolescent psychotherapy. In order to extract as much credible empirical information on this important topic as possible, this meta-analysis will encompass a wider range of relevant research than included in previous meta-analyses through the inclusion of one-group pre-post designs. While admittedly weak in internal validity, such studies are meaningful relative to each other. The statistical comparisons across a broad collection of gain scores simulates a large quasi-experimental comparison group design, allowing questions specific to clinic-based settings to be addressed. The analysis of effect sizes will focus on the overall evidence about the effectiveness of child and adolescent psychotherapy; examination of variation in effect associated with different treatment types, circumstances, settings, dosage, and implementation; examination of variation in effects associated with different client characteristics; and examination of the role of research method and procedure in shaping study results. The proposed studies exploits existing empirical findings and is expected to advance our understanding of the apparent disparity between efficacy and effectiveness studies of child and adolescent psychotherapy.